ETSI ETS 300 913 ed.7 (1999-07)

Digital cellular telecommunications system (Phase 2+) (GSM); General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS) (GSM 07.01 version 5.9.1 Release 1996)

RE/SMG-040701QR9

Digitalni celični telekomunikacijski sistem (faza 2+) – Splošno o terminalskih prilagajalnih funkcijah za mobilne postaje (MS) (GSM 07.01, različica 5.9.1, izdaja 1996)

General Information

• Status: Published
• Publication Date: 20-Jul-1999
• Technical Committee: SMG 4 - Data Services
• Current Stage: 12 - Completion
• Due Date: 23-Jul-1999
• Completion Date: 21-Jul-1999
• Ref Project: SIST ETS 300 913 E7:2003 - Digital cellular telecommunications system (Phase 2+) (GSM); General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS) (GSM 07.01 version 5.9.1 Release 1996)

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±6SORãQRRWHUPLQDOVNLK
SULODJDMDOQLKIXQNFLMDK]DPRELOQHSRVWDMH06*60UD]OLþLFDL]GDMD

Digital cellular telecommunications system (Phase 2+) (GSM); General on Terminal
Adaptation Functions (TAF) for Mobile Stations (MS) (GSM 07.01 version 5.9.1 Release
1996)
Ta slovenski standard je istoveten z: ETS 300 913 Edition 7
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 913
TELECOMMUNICATION July 1999
STANDARD Seventh Edition
Source: SMG Reference: RE/SMG-040701QR9
ICS: 33.020
Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
Digital cellular telecommunications system (Phase 2+);
General on Terminal Adaptation Functions (TAF)
for Mobile Stations (MS)
(GSM 07.01 version 5.9.1 Release 1996)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Internet: [e-mail] - http://www.etsi.org
Tel.: [phone] - Fax: [phone]
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1999. All rights reserved.

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Standards Making Support Dept." at the address shown on the title page.

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
Contents
Intellectual Property Rights.5
Foreword .5
1 Scope .7
2 Normative references.7
3 Abbreviations.9
4 Access reference configuration.10
5 Functions to support data services .10
6 Support of non transparent Bearer Services.11
6.1 Functions of the Layer 2 Relay .11
6.2 Radio Link Services Used.13
6.3 Flow Control - General Description.13
6.3.1 End to End Flow Control.13
6.3.2 Back Pressure.13
6.3.3 Receive not Ready .14
7 Structure of the GSM 07-series of Specifications .14
8 Functions common to all interfaces.14
8.1 Synchronization of the Traffic Channel.14
8.2 Filtering of Channel Control Information .16
8.2.1 General.16
8.2.2 Filtering process to be applied .16
8.3 Terminal Compatibility Decision.17
8.3.1 Compatibility Check.18
8.3.2 Selection of Appropriate Terminal Function .18
8.3.3 Indication of Compatibility Requirements to the PLMN.18
8.3.3.1 Indication in case of Mobile terminating calls .18
8.3.3.2 Indication in case of Mobile originating calls.20
8.4 Test Loops .21
8.5 Alternate speech/data and speech/facsimile group 3.21
8.6 Multislot configuration spit/combine function .22
8.6.1 Non-transparent data .22
8.6.2 Transparent data.22
Annex A (Informative): List of Bearer Capability Elements .23
Annex B (Normative): Setting of Bearer Capability, Low Layer Compatibility and High Layer
Compatibility Information Element for GSM Bearer Services and GSM
TeleServices.30
B.0 Scope .30
B.1 Bearer Capability Information Element.30
B.1.1 Introduction .30
B.1.1.1 General Consideration .30
B.1.1.2 Interpretation of the Diagrams.31
B.1.2 Bearer Service 20 . 26, Data Circuit Duplex Asynchronous .41
B.1.2.1 Unrestricted / restricted digital information transfer capability.41
B.1.2.2 3.1 kHz audio ex-PLMN information transfer capability .43

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
B.1.3 Bearer Service 30 . 34, Data Circuit Duplex Synchronous. 45
B.1.3.1 Unrestricted digital information transfer capability. 45
B.1.3.1.1 Non-X.32 Cases. 45
B.1.3.1.2 X.32 Case (Packet Service). 46
B.1.3.1.4 48kbit/s and 56 kbit/s transparent Case. 48
B.1.3.1.5 64kbit/s bit transparent Case . 49
B.1.3.2 3.1 kHz audio ex-PLMN information transfer capability. 50
B.1.3.2.1 Non-X.32 Cases. 50
B.1.3.2.2 X.32 Case (Packet Service). 51
B.1.4 Bearer Service 40 . 46, PAD Access Asynchronous. 52
B.1.5 Bearer Service 50 . 53 ,Data Packet Duplex Synchronous, Unrestricted digital
information transfer capability . 53
B.1.6 Bearer Service 61, Alternate Speech/Data . 54
B.1.6.1 Bearer Service 61,Speech. 54
B.1.6.2 Bearer Service 61, 3.1 kHz audio ex-PLMN information transfer capability. 55
B.1.6.2.1 Asynchronous . 55
B.1.6.2.2 Synchronous . 56
B.1.7 Bearer Service 81, Speech followed by Data. 57
B.1.7.1 Bearer Service 81,Speech. 57
B.1.7.2 Bearer Service 81, 3.1 kHz audio ex-PLMN information transfer capability. 57
B.1.7.2.1 Asynchronous . 57
B.1.7.2.2 Synchronous . 57
B.1.8 Teleservice 11 . 12, Speech. 57
B.1.9 Teleservice 21 . 23, Short Message. 57
B.1.10 Teleservice 61, Alternate Speech and Facsimile group 3. 57
B.1.10.1 Teleservice 61, Speech . 57
B.1.10.2 Teleservice 61, Facsimile group 3. 58
B.1.11 Teleservice 62, Automatic Facsimile group 3 . 58
B.1.12 Valid combinations of FNUR, WAIUR, ACC, mTCH. 59
B.1.12.1 Transparent Services. 59
B.1.12.2 Non-transparent services. 59
B.2 Low Layer/High Layer Compatibility Information Element . 60
B.2.1 Introduction. 60
B.2.1.1 General Consideration. 60
B.2.1.2 Interpretation of the Tables. 61
B.2.2 LLC Bearer Service 21 . 26. 62
B.2.2.1 Unrestricted / restricted digital information transfer capability . 62
B.2.2.2 3.1 kHz audio ex-PLMN information transfer capability. 62
B.2.3 LLC Bearer Service 31 . 34. 63
B.2.3.1 Unrestricted / restricted digital information transfer capability . 63
B.2.3.2 3.1kHz audio ex-PLMN information transfer capability. 63
B.2.4 LLC Bearer Services 41 . 46 . 64
B.2.5 LLC Bearer Services 51 . 53 . 64
B.2.5.1 Unrestricted digital information transfer capability. 64
B.2.6 LLC Bearer Service 61.64
B.2.6.1 3,1 kHz audio ex-PLMN information transfer capability, Asynchronous. 64
B.2.6.2 3,1 kHz audio ex-PLMN information transfer capability, Synchronous. 64
B.2.7 LLC Bearer Service 81.64
B.2.7.1 3,1 kHz audio ex-PLMN information transfer capability, Asynchronous. 64
B.2.7.2 3,1 kHz audio ex-PLMN information transfer capability, Synchronous. 64
B.2.8 HLC Teleservices 11 . 12. 65
B.2.9 HLC Teleservices 21 . 23. 65
B.2.10 HLC Teleservice 61. 65
B.2.11 HLC Teleservice 62. 65
Annex C (Informative): Change Request History.66
History. 67

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The
information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-
members, and can be found in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially
Essential, IPRs notified to ETSI in respect of ETSI standards", which is available free of charge from the
ETSI Secretariat. Latest updates are available on the ETSI Web server (http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI.
No guarantee can be given as to the existence of other IPRs not referenced in SR 000 314 (or the
updates on the ETSI Web server) which are, or may be, or may become, essential to the present
document.
Foreword
This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
(SMG) Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS outlines the functions needed for terminal adaptation within the digital cellular
telecommunications system (Phase 2+).
The contents of this ETS is subject to continuing work within SMG and may change following formal SMG
approval. Should SMG modify the contents of this ETS, it will be resubmitted for OAP by ETSI with an
identifying change of release date and an increase in version number as follows:
Version 5.x.y
where:
5 indicates GSM Release 1996
x the second digit is incremented for all changes of substance, i.e. technical enhancements,
corrections, updates, etc.
y the third digit is incremented when editorial only changes have been incorporated in the
specification.
Transposition dates
Date of adoption of this ETS: 23 July 1999
Date of latest announcement of this ETS (doa): 31 October 1999
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 April 2000
Date of withdrawal of any conflicting National Standard (dow): 30 April 2000

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
1 Scope
This European Telecommunications Standard (ETS) is based on the principles of terminal adaptor
functions presented in the CCITT I-series of recommendations (I.460 - I.463).
The GSM PLMN supports a wide range of voice and non-voice services in the same network. In order to
enable non-voice traffic in the GSM PLMN there is a need to connect various kinds of terminal equipments
to the Mobile Termination (MT). The target of this ETS is to outline the functions needed for the terminal
adaptation.
In the GSM 02.02 (ETS 300 904) the bearer services are described. The general network configuration is
described in GSM 03.02 and the GSM PLMN access reference configuration is defined in GSM 04.02.
The various connection types used in the GSM PLMN are presented in GSM 03.10. Terminology used in
this ETS is presented in GSM 01.04 (ETR 350). For support of data services between GSM PLMN and
other networks see GSM 09-series of Specifications.
2 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references, the
latest edition of the publication referred to applies.
[1] GSM 01.04 (ETR 350): "Digital cellular telecommunication system (Phase 2);
Abbreviations and acronyms".
[2] GSM 02.02 (ETS 300 904): "Digital cellular telecommunication system
(Phase 2+); Bearer Services (BS) supported by a GSM Public Land Mobile
Network (PLMN)".
[3] GSM 02.03 (ETS 300 905): "Digital cellular telecommunication system
(Phase 2+); Teleservices supported by a GSM Public Land Mobile Network
(PLMN)".
[4] GSM 03.02: "Digital cellular telecommunication system (Phase 2+); Network
architecture".
[5] GSM 03.10: "Digital cellular telecommunication system (Phase 2+); GSM Public
Land Mobile Network (PLMN) connection types".
[6] GSM 04.02: "Digital cellular telecommunication system (Phase 2+); GSM Public
Land Mobile Network (PLMN) access reference configuration".
[7] GSM 04.08 (ETS 300 940): "Digital cellular telecommunication system
(Phase 2+); Mobile radio interface layer 3 specification".
[8] GSM 04.21 (ETS 300 945): "Digital cellular telecommunication system
(Phase 2+); Rate adaption on the Mobile Station - Base Station System
(MS - BSS) interface".
[9] GSM 04.22 (ETS 300 946): "Digital cellular telecommunication system
(Phase 2+); Radio Link Protocol (RLP) for data and telematic services on the
Mobile Station - Base Station System (MS - BSS) interface and the Base Station
System - Mobile-services Switching Centre (BSS - MSC) interface".
[10] GSM 05.05 (ETS 300 910): "Digital cellular telecommunication system
(Phase 2+); Radio transmission and reception".
[11] GSM 07.02 (ETS 300 914): "Digital cellular telecommunication system
(Phase 2+); Terminal Adaptation Functions (TAF) for services using
asynchronous bearer capabilities".

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
[12] GSM 07.03 (ETS 300 915): "Digital cellular telecommunication system
(Phase 2+); Terminal Adaptation Functions (TAF) for services using
synchronous bearer capabilities".
[13] GSM 07.05: "Digital cellular telecommunication system (Phase 2+); Use of Data
Terminal Equipment - Data Circuit terminating Equipment (DTE - DCE) interface
for Short Message Service (SMS) and Cell Broadcast Service (CBS)".
[14] GSM 07.07 (ETS 300 916): "Digital cellular telecommunication system
(Phase 2+); AT command set for GSM Mobile Equipment (ME)
[15] GSM 09.01 (ETR 359): "Digital cellular telecommunication system (Phase 2);
General network interworking scenarios".
[16] GSM 09.02 (ETS 300 974): "Digital cellular telecommunication system
(Phase 2+); Mobile Application Part (MAP) specification".
[17] GSM 09.03: "Digital cellular telecommunication system; Signalling requirements
on interworking between the Integrated Services Digital Network (ISDN) or
Public Switched Telephone Network (PSTN) and the Public Land Mobile
Network (PLMN)".
[18] GSM 09.04: "Digital cellular telecommunication system; Interworking between
the Public Land Mobile Network (PLMN) and the Circuit Switched Public Data
Network (CSPDN)".
[19] GSM 09.05: "Digital cellular telecommunication system; Interworking between
the Public Land Mobile Network (PLMN) and the Packet Switched Public Data
Network (PSPDN) for Packet Assembly/Disassembly (PAD) facility access".
[20] GSM 09.06 (ETS 300 975): "Digital cellular telecommunication system
(Phase 2+); Interworking between a Public Land Mobile Network (PLMN) and a
Packet Switched Public Data Network/Integrated Services Digital Network
(PSPDN/ISDN) for the support of packet switched data transmission services".
[21] GSM 09.07 (ETS 300 976): "Digital cellular telecommunication system
(Phase 2+); General requirements on interworking between the Public Land
Mobile Network (PLMN) and the Integrated Services Digital Network (ISDN) or
Public Switched Telephone Network (PSTN)".
[22] GSM 09.08: "Digital cellular telecommunication system; Application of the Base
Station System management Application Part (BSSMAP) on the E-interface".
[23] GSM 09.10: "Digital cellular telecommunication system (Phase 2+); Information
element mapping between Mobile Station - Base Station System and BSS -
Mobile-services Switching Centre (MS - BSS - MSC) Signalling procedures and
the Mobile Application Part (MAP)".
[24] GSM 09.11: "Digital cellular telecommunication system (Phase 2+); Signalling
interworking for supplementary services".
[25] GSM 09.90: "Digital cellular telecommunication system (Phase 2+); Interworking
between Phase 1 infrastructure and Phase 2+ Mobile Stations (MS)".
[26] CCITT Series V Recommendations: "Data communication over the Telephone
network".
[27] CCITT Series V.42bis: "Data Compression for Data Circuit Terminating
Equipment (DCE) using Error Correction Procedures".
[28] CCITT Series X Recommendations: "Data Communication networks”.

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
[29] CCITT Recommendation X.25 "Interface between data terminal equipment
(DTE) and data circuit - terminating equipment (DCE) for terminals operating in
the packet mode and connected to public data networks by dedicated circuit".
[30] CCITT Recommendation X.150: "Data Communication Networks: Transmission,
Signalling and Switching, Network Aspects, Maintenance and Administrative
Arrangements".
[31] CCITT Recommendation V.25bis: "Automatic Calling and/or Answering
Equipment on the General Switched Telephone Network (GSTN) using the 100-
Series Interchange Circuits".
[32] ITU-T Recommendation V.25ter: "Serial asynchronous automatic dialing and
control".
[33] CCITT Recommendation V.54: "Loop Test Devices for Modems".
[34] CCITT Recommendation V.110: "Support of data terminal equipments (DTEs)
with V-Series interfaces by an integrated services digital network".
[35] CCITT Recommendation I.460-I.464: "ISDN Overall Network Aspects and
Functions, User Network Interfaces".
[36] ETS 300 102-1: "Integrated Services Digital Network (ISDN); User-network
interface layer 3 specifications for basic call control".
[37] ETR 018: "Integrated Services Digital Network (ISDN), Application of the BC-,
HLC-, LLC-Information elements by terminals supporting ISDN services".
[38] ISO/IEC 6429: "Information technology - Control functions for coded character
sets".
[39] Personal Computer Memory Card Association: "PCMCIA 2.1 or PC-Card 3.0
electrical specification or later revisions".
[40] IrDA "IrPHY Physical signalling standard".
[41] TIA-617: "Data Transmission Systems and Equipment - In-Band DCE Control".
[42] CCITT Recommendation V.120: "Support by an ISDN of data terminal
equipment with V-Series type interfaces with provision for statistical
multiplexing".
[43] GSM 03.34 (TS 101 038):”Digital cellular telecommunication system (Phase 2+);
High Speed Circuit Switched Data (HSCSD); Stage 2 Service description”.
3 Abbreviations
In addition to those below, abbreviations used in this ETS are listed in GSM 01.04.
CALL PROC CALL PROCEEDING
CALL CONF CALL CONFIRMED
CONNACK CONNECT ACKNOWLEDGEMENT

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
4 Access reference configuration
Figure 1 presents the reference configuration for access to a GSM PLMN (see GSM 04.02).
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568P
¶À¶ = reference point
TE1 = ISDN terminal
TE2 = V- or X-type terminal
TA = Terminal Adaptor
BSS = Base Station System
MSC = Mobile Switching Centre
Figure 1: GSM PLMN Access Reference Configuration
Within the scope of this ETS the Mobile Termination MT0 means a fully integrated MS including data
terminal and its adaptation functions. MT1 includes ISDN terminal adaptation functions and MT2 includes
CCITT V- or X-series terminal adaptation functions among other MT functions.
5 Functions to support data services
The main functions of the MT to support data services are:
- functions to ensure conformity of terminal service requests to network capability;
- physical connection of the reference points R and S;
- flow control of signalling and mapping of user signalling to/from GSM PLMN access signalling;
- rate adaptation of user data (see GSM 04.21);
- flow control of non-transparent user data and mapping of flow control for asynchronous data
services;
- support of data integrity between the MS and the interworking function in the GSM PLMN;
- end-to-end synchronization between terminals;
- filtering of status information;
- functions to support non-transparent bearer services e.g. termination of the Radio Link Protocol
(RLP) and the Layer 2 Relay function (L2R) including optional data compression function (where
applicable);
- terminal compatibility checking;
- optional support of local test loops.

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
In addition, functions to support autocalling and autoanswering are optionally specified in accordance with
CCITT Rec. V.25 bis or with ITU-T Rec. V.25 ter (although the use of other autocalling/auto-answering
procedures are not prohibited provided that mapping in a functionally equivalent way to GSM 04.08 call
control is also provided).
Other functional entities can be envisaged apart from the TAF. One of the physical interface to all these
functions is the DTE/DCE interface to the MT. Normally, this DTE/DCE interface is associated with the
TAF, if available. Therefore the access to any of these other functional entities, if implemented, via the
DCE/DTE interface must be triggered by appropriate command sequences which are described in the
applicable specifications (although the use of other procedures is not prohibited provided that mapping in
a functionally equivalent way is also provided). These command sequences can be issued by the DTE
only when the MT is in the appropriate command status and there is no data connection pending. They
are interpreted by an MT internal control function and result in an association of the DTE/DCE interface
with the addressed function, if available.
6 Support of non transparent Bearer Services
In order to support non transparent bearer services a Layer 2 Relay (L2R) function is included in the
mobile termination. The details of the particular L2R function for the different non transparent bearer
services are contained in the appropriate GSM 07-series Specification. This section describes the general
aspects of the L2R function.
The Layer 2 Relay (L2R) function provides for the reliable transportation of known, i.e. non transparent,
user protocols across the radio interface of a GSM PLMN. The L2R functions are located in the Mobile
Termination (MT) and the Interworking Function (IWF) associated with a Mobile Switching Centre (MSC).
The L2R uses the services provided by the Radio Link Protocol (RLP) to transport the non transparent
protocol information between the MS and the IWF.
6.1 Functions of the Layer 2 Relay
The complete protocol reference models for data and telematic services are described in GSM 03.10. The
subset of those protocol reference models relating to the L2R function is reproduced in figure 2.
06,:)
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Figure 2
The Non Transparent Protocol (NTP) will normally be a layer 2 protocol for OSI conformant protocols or
an equivalent in the case of non OSI protocols. The Interface Protocol (IFP) will normally be a layer 1
protocol for OSI conformant systems or equivalent for non OSI systems.
The L2R can be considered to consist of 3 sub-functions, see figure 3.

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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
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ETS 300 913 (GSM 07.01 version 5.9.1 Release 1996): July 1999
The 3 sub-functions are:
- A Non Transparent Protocol Entity
- A L2R Protocol Entity
- A Relay Entity
The NTP-entity interfaces the L2R to the IFP-entity and provides an interface to the particular NTP.
The L2RP-entity interfaces the L2R to the RLP-entity and provides an interface to the appropriate L2R
protocol.
The Relay-entity provides the mapping between the NTP-entity and the L2R-entity. If applicable, it
contains the data compression function. The negotiable parameters are exchanged with the remote
Relay-entity by means of the RLP XID frame.
It should be noted that the inter-layer interfaces within the MS and the IWF and within the L2R will not be
specified by GSM, any description given is for explanatory purposes only and is not intended to indicate a
method of implementation. Therefore, the specification of the L2R is in terms of the peer-peer protocols.
Generally, the non transparent and interface protocols will be specified elsewhere, e.g. CCITT
Recommendation X.25 Layer 2 and 1. Thus the main specification for the L2R will consist of the L2R
peer-peer protocols.
6.2 Radio Link Services Used
The L2R function uses services defined in GSM Specification 04.22 (Radio Link Protocol).
6.3 Flow Control - General Description
A flow control active condition can take place under a number of circumstances:
- End to end flow control (DTE to DTE matter);
- Backpressure (buffers filling);
- Receive not ready (RLP condition).
It is possible that there will be an interaction between flow control active and inactive conditions in each
circumstance.
6.3.1 End to End Flow Control
A DTE may wish to send a flow control active condition to another DTE.
Provisions exists in the L2R entity to transfer a flow control active condition (sent by its associated DTE) to
the other L2R entity as soon as possible. This mechanism in the L2R entities allows such a flow control
condition to be put ahead of any queuing which exists in the L2R entities.
Such a mechanism avoids build up of data in buffers which can be undesirable.
The L2R entity, receiving a flow control active condition from its associated DTE, stops sending data to
that associated DTE immediately.
6.3.2 Back Pressure
The L2R and RLP entities have buffers which may become full to a predetermined threshold for a number
of reasons, e.g. severe radio fading, failure or slowness of DTE to react to end to end flow control, certain
RNR conditions. When this predetermined threshold is reached, a flow control active condition is sent to
the associated DTE which is then prevented from sending any data, subsequently, the flow control inactive
condition is sent to the associated DTE when the L2R or RLP entities have indicated that there is sufficient
free capacity in their buffers for data flow from the associated DTE to proceed.
The corresponding peer-layer procedure to assess the respective buffer conditions are a layer
management matter and are not dealt with here. It is also considered an implementation matter to ensure
that such procedure do not result in loss of data or considerable reduction in throughput.

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6.3.3 Receive not Ready
When the RNR condition arises, an RLP indication is sent to the other RLP entity which in turn shall send
a flow control active condition to its associated L2R entity. That L2R entity shall then send a flow control
active condition to its associated DTE.
An RNR condition may result in the Execution of "back pressure" as mentioned under 6.3.2.
7 Structure of the GSM 07-series of Specifications
The structure of the Specifications is as follows:
07.01 General on Terminal Adaptation Functions for Mobile Stations
07.02 Terminal Adaptation Functions for Services using Asynchronous Bearer
Capabilities
This Specification defines the interfaces and terminal adaption functions integral
to a MT which enable the attachment of Asynchronous Terminals to a MT.
07.03 Terminal Adaptation Functions for Services using Synchronous Bearer
Capabilities
This Specification defines the interfaces and terminal adaptation functions
integral to a MT which enable the attachment of Synchronous Terminals to a
MT.
8 Functions common to all interfaces
8.1 Synchronization of the Traffic Channel
As long as there is no connection between the traffic channel and the interface to the TE this interface
must be terminated in the appropriate way.
Prior to exposing the traffic channel of a GSM PLMN connection to transmission of user data, the
controlling entities of the connection have to assure of the availability of the traffic channel(s). This is done
by the so called synchronization process:
- starting on the indication of "physical connection established" resulting from the PLMN inherent
outband signalling procedure. This indication is given on reception of the message CONNECT in
case of MOC, on reception of the message CONNACK in case of MTC and on reception of the
message MODIFY COMPLETE in case of in-call modification.
- ending by indicating the successful execution of this process to the controlling entity, which then
takes care of the further use of the inband information (data, status).
With respect to the TAF for the transparent bearer capability support the synchronization procedure with
the channel codings 2.4, 4.8 and 9.6 kbit/s is as follows:
- sending of synchronization pattern 1/OFF (all data bits "1" / all status bits "OFF", all E-bits "1") to the
IWF. In multislot transparent operation, the synchronisation pattern sent is 1/OFF with the exception
of the bit positions S1, first X, S3, and S4 which contain the substream number and multiframe
alignment pattern (Ref. GSM TS 04.21);
- searching for detection of the synchronization pattern received from the IWF, and in multislot
operation, also searching for the multiframe alignment pattern “0000 1001 0110 0111 1100 0110
1110 101” (Ref. to GSM 04.21) in bit position S4 and substream numbers in bit positions S1, first X,
and S3. The value of the bits E4-E7 shall not be checked;
- holding CT106, 107 and 109 in the OFF condition;
With respect to the TAF for the transparent bearer capability support the procedure with the TCH/F14.4 is
as follows:
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- sending of synchronization pattern 1/OFF (all data bits "1" / status bits in M2 "OFF") to the network
in the multiframe structure with the multiframe alignment pattern pattern “0000 1001 0110 0111
1100 0110 1110 101” in the M1 (Ref. to GSM TS 4.21) and, in a multislot case, sending substream
numbers in the bit M2
- searching for the detection of the multiframe alignment pattern “0000 1001 0110 0111 1100 0110
1110 101” (Ref. to GSM 04.21) in the bit M1 originating from the network, and, in a multislot case,
searching for substream numbers in the bit M2. (Any 5 bit sequence in the multiframe alignment
pattern is unique, i.e. the multiframe alignment can take place by the recognition of five successive
S1 bits.)
- holding CT106, 107 and 109 in the OFF condition;
When the synchronisation pattern and, in case of multislot operation or TCH/F14,4, the multiframe
alignment pattern from the IWF have been recognized as a steady state (see note 1) the TAF continues
sending the synchronization patterns to the IWF unless a timer T (=500ms) expires.
NOTE 1: - An idle frame sent by the BSS and received by the MS has the same pattern as the
synchronization pattern 1/OFF.
- At the moment when the message CONNECT (MOC) or CONNACK (MTC) is
received at the MS, it is guarantied that this pattern is received from the MSC/IWF with
the exception of a loss of frame synchronization on the Abis interface.
- The handling of frame stealing in case of 2400 bit/s full rate data channels is
implementation dependent.
From this time, after the expiration of the timer T of each allocated traffic channel for the call, the filtering
process according to section 8.2 applies and the information on the receiving lines CT106 and CT109 (M2
bit in the TCH/F14.4 case, ref to GSM 04.21) from the IWF are directly mapped to the respective sending
lines. The condition on CT107 will be changed from "OFF" to "ON", the data bits received from the IWF
are mapped to CT104, and CT103 is mapped to the data bits sent towards the IWF.
During the synchronization process described above i.e. while the synchronization pattern is being sent by
the MT, the MT will not send the V.110 frame structure to the ISDN terminal. Once the timer T of each
traffic channel(s) allocated for the call expires the synchronization pattern will continue to be transmitted
from the MT to the IWF, however, the MT will start sending the V.110 frames received from the IWF to the
ISDN terminal. The MT will start looking for the ISDN frame alignment to be received from the ISDN
terminal. On recognizing frame alignment the MT will cease sending its synchronization pattern to the IWF
and connect the ISDN terminal through to the IWF. In case of multislot operation or TCH/14.4 the MT shall
adapt the data stream as defined in GSM TS 04.21.
With respect to the TAF for non-transparent bearer capability support the synchronization procedure is as
follows:
- receiving V.110 frames on all allocated traffic channels for the call
- initiating the RLP link establishment by sending a RLP-SABM across the radio interface.
- holding CT106, 107, 109 in the OFF condition.
When the RLP link has been established, CT107 will be changed from "OFF" to "ON". From this time the
information from/to the RLP, including status changes, will be mapped by the L2R entity applicable to the
particular bearer capability. The MT will not send V.110 frame structure to the ISDN terminal and will not
start looking for ISDN frame alignment to be received from the ISDN terminal unless the RLP link has
been established. On recognizing frame alignment the information from/to the RLP will be mapped by the
L2R entity.
It should be noted that in a GSM PLMN V.-series and X.-series interfaces are only supported in full duplex
mode. Thus the call control phase can be mapped almost completely to the signalling procedure (the S-
bits during the call control phase are irrelevant). However, the "ready for data" condition (i.e. CT 106/109,
in the case of V.-series interface, and I-circuit, in the case of X.-series interface) is derived directly from
the traffic channel (see also filtering of channel information).

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8.2 Filtering of Channel Control Information
8.2.1 General
The DTEs taken into account for the PLMN at the MS side conform to CCITT's DTE/DCE interface
specifications, which assume basically an error-free environment, i.e.
- limited distance, point-to-point local interconnection of the interface circuits for data and status;
- steady state signalling.
The envisaged use of these DTEs in the PLMN environment leads to the exposure of these
"interconnections" to the PLMN radio channel. To assure proper operation even under these conditions
appropriate measures have to be taken. In the non transparent case the RLP satisfies the requirement for
both data and status lines.
In the transparent case the
- data line aspects have to be dealt with end-to-end between the users, while
- status line aspects are of concern to the network, which are dealt with in the following.
8.2.2 Filtering process to be applied
Filtering of channel control information is only relevant at the MS side in the transparent mode of
operation. By applying filtering measures the condition of a DTE/DCE control interchange circuit, for which
the DTE constitutes the information sink, will be preserved until another condition is signalled for an
"integration time" period by the channel control information (status bits) of the rate adaptation scheme.
The filtering mechanism is understood to reside between the rate adaptation function (information source)
and the DTE (information sink). It receives the unfiltered condition of the respective control interchange
circuit set according to the actual sequential appearance of the individual associated status bit and
forwards the filtered condition to the DTE.
The filtering process starts when the traffic channel synchronization ends with the expiry of timer T.
V.-series interface
CT 106
In the transparent mode the remote inband control of this circuit is needed to support a modem retrain
procedure.
OFF-ON transition at the MS will authorize the DTE to send data; if wrongly set, loss of data may occur.
ON-OFF transition at the MS will cause the DTE to cease transmitting data; set wrongly may impair the
performance in connection usage.
CT 109
In the transparent mode the remote inband control of this circuit is needed to:
- trigger the interpretation of received data;
- indicate to the DTE the state of the connection.
OFF-ON transition at the MS will authorize the DTE to rely on the condition of the received data
interchange circuit, set wrongly may cause receipt of wrong data, while setting late may cause loss of
data.
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ON-OFF transition at the MS:
- will cause the DTE to cease receiving data;
- may initiate release of the connection during a data phase by the DTE giving an ON-OFF transition
on circuit 108/2.
Setting this condition wrongly may cause loss of data and potentially release the connection.
X.-series interface
I-circuit
The OFF-ON transition of this circuit in connection with the appropriate conditions of the other interchange
circuit will indicate the "ready for data" status of the connection. As received data may commence
immediately following this status change, the delay in conveying this condition shall be kept as short as
possible.
As a clear request/indication will be directly mapped to the PLMN outband signalling the ON-OFF
integration time should be rather long.
Filtering me
...